Railway traffic controlling apparatus



Jan. 12, 1943. Y R. KEMMERER ETAL 2,398,238

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed April 3, 194; 2 Sheets-Sheet 1 INVENTORSI Y Ralph fii mmepe a1zd(' [Sm 210s THEIR n'rl oRNEY Jan. 12, 1943 R. R. KEMMERER ET AL 2,303,288

RAILWAY TRAFFIG CONTROLLING APPARATUS Filed April 3, 1941 2 Sheets-Sheet 2 TZE I RC Cl 31 INVENTQRS I .lfammepep and ESfU JIQS BY 7 10,71: A'TTORNEY Patented Jan. 12, 1943 RAILWAY TRAFFIC CONTROLLING APPARATUS Ralph E. Kemmerer, Swissvale, and Crawford E; Staples, Edgewood, Pa., assignors to The Union Switch & Signal Company, Swissvale, Pa, a corporation of Pennsylvania Application April 3, 1941, Serial No. 386,633

-16 Claims.

Our invention relates to railway trarfic con trolling apparatus, and it has particular reference to the organization of such apparatus into novel and improved means for obtaining directional control of trafiic in absolute permissive block (A.

trafiic in both directions on a single track stretch,

to provide each intermediate signal with a directional stick relay jointly controlled by track circuits and line wirecircuits, the latter of which involve the use of control line wires extending along the trackway. These stick relays as employed in the usual line-wire A. P. B. systems are ordinarily controlled by circuits so arranged that when a train enters the stretch, the stick relays associated with the signals governing trafiic in the direction of the train movement are successively caused to be picked up as the train moves through the stretch. A stick relay for example may be picked up when the train enters the section governed by the associated signal, and such stick relay is held energized over a stick circuit during the interval that the train occupies such section. Means are also provided for preventing the pick-up of the stick relays associated with the signals governing traflie movements in the opposite direction, and the stick relays are normally employed to control the supply of track circuit and/or line wire energy to the section in the rear of each associated signal and thus effect control of the signal of such rear section to obtain proper spacing of following trains on the track.

Various systems have been proposed involving apparatus arranged so as to obviate the line wires ordinarily required in A. P. B. systems. One such system is shown and claimed in a copending application, Serial No. 294,897, filed on September 14, 1939, by Ralph R. I'Zernmerer now U. S; Letters Patent 2,280,491 granted April 21, 1942, and assigned to the assignee of the present application. An improved system of this class is described in detail and claimed in a copending application, Serial No. 386,632, filed by us on April 3, 1941, for Absolute permissive block system of railway signaling, now U. 55. Letters Patent 2,283, 998 granted May 26, 1942, and it is to be understood that various features shown but not claimed in the present application are claimed in our said copending application. Other features also shown but not claimed in the present application form the subject matter of another copending application, Serial No. 382,431 filed on March 8, 1941, by Frank H. Nicholson and of common ownership herewith.

An object of our present invention is the provision of novel and improved directional control apparatus particularly suitable for use in railway signal systems provided for a stretch of single track railway over which traffic operates in either direction.

Another object of our invention is to provide novel and improved directional control apparatus suitable for use in railway signal systems of the above described class and arranged to be controlled wholly through the medium of trackcircuits.

A further object of our invention is to provide I in railway signal systems of the above described class, directional control means associated with the track circuit supply sources and controlled without the use of line wires solely through the medium of track circuit apparatus.

An additional object is to provide novel and improved directional control means particularly suitable for use in railway signal systems of the class disclosed in the aforesaid Nicholson application, Serial No. 382,431.

A still further object is to provide novel and improved directional control means adapted for use in railway signal systems of the above described class and associated with the track circuit energy supply means employed in such systems in such manner as to provide an approach control of the directional control means.

The above-mentioned and other important objects and characteristic features of our invention which will become readily apparent from the following description, are attained in accordance with our invention by incorporating into a signal system arranged in accordance with the absolute permissive block principle and having a track circuit supply source at the adjacent ends of each two adjoining track sections, directional control means comprising the combination with each of said energy sources of two directional stick relays one associated with one direction of traffic in one of the adjoining two sections and the other stick relay associated with the opposite direction of traffic in the other of the adjoining two sections, and by utilizing apparatus effective upon a train entering the stretch and shunting the rails of the first section of the stretch for causing the coupling with each of the track circuit energy sources of the one of the associated two stick relays associated withthe direction of train movement. This coupling preferably is arranged to be effective to condition the coupled stick relay of a section to be picked ,up when the train occupies the adjoining section in the rear for the direction of train movement, due to the increased track circuit current caused to flow by the train shunt established across the rails of such section, thereby attaining approach control of the directional stick relays by picking up the stick relay associated with the direction of train movement in a section, prior to the train entering the associwhen placed side by side with Fig. la on the left,

constitute a diagrammatic view illustrating a portion of an absolute permissive block signal system incorporating directional control apparatus arranged in accordance with our invention.

In the accompanying drawings, a stretch of single track railway is represented as divided by insulated joints 2 into a plurality of successive adjoining track sections A, B and C. The represented stretch is to be understood as Comprising a portion of the single track over which trains move in either direction between passing sidings or double track portions which are not shown in the drawings.

The single track portion represented in the drawings is provided with apparatus arranged to prevent opposing traffic movements over the stretch while permitting following trains to proceed through the stretch'under permissive signal indications governed by traflic on the stretch. In the drawings is represented apparatus embodying our invention and arranged for use at typical intermediate signal locations, and it is believed that the following description of such apparatus will be sufiicient for a complete understanding of the present invention.

The apparatus represented. at a typical intermediate signal location, for example as at location III which corresponds to the location defined by the adjacent ends of the two adjoining sections A and B, comprises a pair of wayside signals one of which is designated by the reference character SE with a suitably distinguishing suflix and governs traffic in the adjoining section B operating in the eastbound direction or from left to right as viewed in the drawings, and the other signal of which is designated by the reference character SW with a suitably distinguishing suffix and governs westbound traiiic in the other adjoining section A. These signals may be of any suitable form and as shown comprise three-indication signals having a plurality of lamps G, Y

and R, which lamps when illuminated indicate clear, approach and stop, respectively.

Each intermediate signal location is provided with a source of track circuit energy adapted to supply energy to the rails of one or the other of the two adjoining sections. At location III, for example, a suitable source of alternating current, such as a generator not shown but having its two terminals designated by the reference characters BXCX, is provided for supplying track circuit energy at times to the rails of one and at other times to the rails of the other of the two adjoiningsections A and B. Track transformers, designated by the reference characters TT with suitably distinguishing sufiixes, are provided at each signal location one for each adjacent end of the two adjoining sections for coupling the source BX-CX to the rails of one or the other of the two adjoining sections. Each section extending between successive intermediate signal locations, as for example section B, accordingly is provided with two track transformers one connected across the rails at each end of the section. 1

In accordance with our present invention, each intermediate signal location of the stretch is provided with apparatus arranged to effect the usual A. P. B. directional control of the associated signals. For example, location III is provided with apparatus embodying our invention and comprising the usual two directional stick relays ES and WS, one associated with the signal governing traific movements in one direction in one of the two adjoining sections and the other associated with the signal governing traffic movements in the opposite direction in the other of the two adjoining sections. For the purposes of the present description, we shall assume that relay ES at III is associated with signal SEIII governing eastbound trafiic in section B, and that relay WS at III is associated with signal SWIII governing westbound traific in section A. These relays are normally released, and are arranged to be controlled in such manner that when a train enters the single track stretch, the one of the two relays associated with the direction of train movement is conditioned to be picked up in response to movement of the train through the stretch. More particularly, this arrangement involves means for coupling the stick relay associated with the direction of train movement to the track circuit energy supply source located at the. associated intermediate signal location. The coupling preferably is arranged to be effective to condition the coupled stick relay to be picked up when the train occupies the section in the rear of the associated signal and the low resistance path established across the track circuit source by the train wheels and axles causes an increased current to flow in the track rails of such section.

To efiect the above-mentioned coupling, each intermediate signal location is provided with a transformer EWS comprising a primary winding track transformers TT and the other winding 1 interposed in the connection of the source to the other of the associated two track transformers. The function of the two windings 6 and 1 of transformer EWS will be made clear presently. Each transformer EWS further comprises a secondary winding 8, and each transformer has associated therewith a full-wave rectifier 9 arranged with its input terminals connected across the terminals of secondary winding 13.

The apparatus at each signal location is arranged in such manner that the two directional stick relays at such location are normally uncoupled from the associated track circuit source BXCX, and these relays are normally released as represented in the drawings, Whenever a train enters the stretch, however. at each intermediate signal location the one .of the two stick relays associated with the direction of train movement is connected in circuit with rectifier 9 and hence is coupled to the associated track circuit source BX-CX through the medium of the associated rectifier 3 and transformer EWS. When an eastbound train enters the stretch, for example, relay ES at, III is conditioned .to he picked up, in response to the train movement,

over a circuit extending from one output termi- H nal of rectifier 9 through back contact I!) of the other stick relay WS. back contacts H and I2 of relays HW and HWP associated with section A and later to be referred to, front contact it of relay HEP associated with section B and later to be referred to, and the winding of relay ES to the other output terminal of rectifier 9. Relay ES preferabl is proportion d so that with the just traced circuit completed, the energization effected of relay ES is insufficient to pick up such relay unless a relatively heavy current is drawn through transformer EWS due to a train in section A establishing through its Wheels and axles a low resistance path across the track rails and causing to flow in the rails of such section a relatively heavy rail current. When this happens, relay ES is caused to pick up due to the increased energy available in secondary winding 8 of transformer EWS. Relay ES in picking up closes its front contact E to complete a preliminary stick circuit which may be traced from one terminal of a suitable source of unidirectional current, such as a battery not shown but having its two terminals designated respectively by plus and minus, through front contact to of relay ES, back contact I!) of relay WS, back contacts H and S2 of relays HW and I-IWP, respectively, front contact I3 of relay HEP, and the winding of relay ES to the other terminal of the source. After the train occupies the section with which relay ES is associated, relay ES is provided with another or final stick circuit extending from the one terminal of the source of unidirectional current, through back contact M of relay HE associated with section B and hereinafter referred to, front contact 55 and the winding of relay ES to the other terminal of the source.

Relay ES preferably is of the ordinary acting type and hence ordinarily releases quickly when deenergized. As will be made clear presently, it may at times be desirable to delay the release of this relay, and for this purpose the circuits of relay ES are arranged so as at times to provide short-circuiting or snubbing paths across the relay winding. When front contact !3 of relay HEP is closed, relay ES is provided with an obvious snubbing circuit which includes the winding of relay ES, asymmetrical unit 23 in its low resistance direction, and front contact I3 of relay HEP. Relay ES at times is provided with another snubbing circuit which includes thewinding of relay ES, front contact I l of relay HW, back contact 12 of relay I-IWP, and front con tact [3 of relay HEP.

In the event that a westbound train enters the stretch, then there is provided for relay WS at, III a pick-up circuit extending from one terminal of rectifier 9 through back contact 16 of the other stick relay back, contacts H and I3 of relays HE and I-IEP associated with section B, front contact l2 of relay HWP associated with section A and the winding of relay WS to the other terminal of rectifier 9. Relay WS is ar ranged to be picked up over they above traced circuit only in the event that a relatively heavy rail current is caused to be supplied from the track circuit source BX-CX through transformer EWS to section B due to a train in the section establishing across the track rails a low resistance path comprising the wheels and axles of the train. Whenrelay WS picks up, it completes for itself a preliminary stick circuit which may be traced from one terminal of the unidirectional source through front contact H] of relay WS, back contacts l6, ll and l3 of relays ES, HE and HEP, respectively, front contact 12 of relay HWP and the winding of relay WS to the other terminal of the source. After the train occupies section A, relay WS is energized over a final stick circuit extending from one terminal of the unidirectional source through front contact [8 of relay WS, back contact l9v of relay I-IW and the winding of relay WS to the other terminal of the source.

Relay WS is of the ordinary acting type and has its circuits arranged so as at times to provide across its winding short-circuiting or snubbing paths for delaying its release. One snubbing circuit is provided when front contact I2 of relay I-IWP is closed and this path includes the winding of relay W S, asymmetrical unit 23 in its low resistance direction and front contact IQ of relay HWP. Another snubbing circuit at times completed includes the winding of relay WS, front contact 2? of relay HE, back contact I3 of relay HEP and front contact l2 of relay HWP.

The two stick relays ES and WS at each signal location function to establish directional control of traffic on the stretch in accordance with the usual principle of absolute permissive block signaling, as will be made clear presently.

The above-mentioned control of the stick relays ES and WS at each intermediate signal location of the stretch is effected by signal apparatus arranged in accordance with the usual A. P. B. principle. Although our present invention might be employed to effect control of di rectional stick relays incorporated into A. P. B. signal systems, involving the use of both track circuit and control line wire apparatus, our present invention has particular utility in connection with A. P. B. signal systems involving apparatus arranged so as to eliminate all control line wires and controlled solely through the medium of track circuit apparatus. The apparatus by means of which there is effected the heretofore mentioned control of the directional stick relays at each intermediate signal location is, therefore, represented in the drawings as being arranged to eliminate all control line wires.

The particular arrangement of apparatus represented in the drawings for effecting control of the directional stick relays ES and WS is described in detail and claimed in our heretofore mentioned copending application Serial No. 386,632, and in the present application this apparatus will be described only to the extent deemed necessary for a complete understanding of our present invention. This apparatus, in general, is arranged to provide each section of track with two track circuits one for each direction of traf lie and each arranged to utilize coded track circuit energy. The two track circuits of each section are arranged to be energized during the opposite half cycles constituting the usual frequency type code energy employed in coded track circuits. That is to say, one track circuit of each section is normally supplied with energy coded at one or another of a plurality of code rates of the frequency code type comprising recurrent code cycles each consisting of one on and one off interval during which energy is and is not present respectively in the track rails, and such circuit has a track relay which is energized by and responds to each on interval of the frequency type code energy in the associated section. The other track circuit of each section is arranged to be supplied with feed back type code energy comprising on intervals supplied to the rails during the off intervals of the frequency type code of the section, and such other circuit is provided with a track relay which is energized by and responds to each on interval of the feed back code energy in the associated section. This arrangement involves providing each track section with two track relays one at each end of the section, and means for associating each of such relays with the track transformer TT at such end. Considering section B, for example, one track relay TR located at the left-hand end as viewed in the drawings, or the eastbound entrance end of the section, is associated with track transformer TTW and has associated therewith means for coupling relay TR through transformer TTW to the rails of section B, while the other track relay TRA at the opposite or westbound entrance end of the section is associated with track transformer TTE and has associated therewith means for coupling relay TRA through transformer TTE to the'rails of the asso ciated section B.

The means for coupling relays TR and TRA through transformers TTW and TTE to the rails of the associated section comprise code repeating devices RC and CTP, respectively. Each code repeating device is effective to connect its associ ated track relay to or disconnect such relay from its associated track transformer according as the device is deenergized or energized, respectively.

For example, device RC at III associated with relay TR of section B connects relay TR to or disconnects such relay from track transformer TTW according as contacts 25 and 2! of device RC are in their respective released back positions or are in their attracted front positions. Similarly, device CTP at IV associated with relay TRA of section B connects relay TRA to or disconnects such relay from track transformer TTE according as contacts 39 and 3| of device CTP are in their released back positions or are in their attracted front positions.

The code repeating devices RC and CTP also function to control the supply of track circuit energy to the rails of the associated section. That is to say, when a device CTP is energized it operates its contacts 30 and 3| out of their back positions to uncouple its associated relay TRA from the rails of the associated section, and connects the track circuit source BX-CX to such rails over a circuit to be traced shortly. In a similar manner, when a device RC is energized it disconnects the associated relay TR from the rails of the associated section, and normally connects a source, indicated by the reference charac' ters BK--CX, to the track rails. At times. however, the energization of device RC is effective to couple the track circuit source BXCX to the track rails, as will be made clea'rpresently.

Each code repeating device CTP is normally caused to operate its contact members 30 and 3| alternately into and out of their attracted or front positions in response to code generating means effective to generate codes of the frequency code type. These code generating means may be of any suitable type and may comprise, for example, a plurality of code transmitters or coders, designated by the reference characters CT with suitably distinguishing prefixes, one coder CT for each different code rate employed. As represented in the drawings, coders ICT and IECT are provided at each intermediate signal location for generating codes having the frequencies of, say, and 75 cycles per minute, respectively. Each coder CT is provided with contacts which it operates and which, when interposed in circuits supplied with energy, are effective to interrupt or code such energy at a rate corresponding to the rate of operation of the coder. Each coder CT is constructed and arranged to operate its contacts in a manner so as to produce frequency type code energy, that is, coded energy comprising alternate on and off intervals having substantially equal durations.

Each device RC is normally caused to operate at a rate corresponding to the rate of operation of its associated track relay TR, but at times each device RC is caused to operate in response to the code generating means, as will be made clear presently.

The two track relays TR and TRA of each section have associated therewith the usual frequency code decoding apparatus comprising a decoding transformer designated by the reference character DT with a suitably distinguishing suffix and a plurality of decoding relays one for each different rate of coding utilized. The decoding apparatus associated with relay TR of section B is typical and comprises a transformer DTE controlling two decoding relays HE and DE, the former relay being controlled by relay TR through the medium of transformer DTE in such manner that relay HE is picked up whenever relay TR follows energy coded at anycode rate, hence relay HE comprises a code detecting relay. Relay DE is controlled by relay TR through the medium of transformer DTE and a decoding'unit I80DU arranged to pass current and energize relay DE when and only when relay TR follows energy coded at a particular one of the plurality of code rates, such as for example a code rate of 180 cycles per minute. a

Each code detecting relay HE and HW has as sociated therewith a slow'acting repeater relay, designated by the reference character P with a prefix corresponding to the reference character of its associated code detecting relay. Each slow acting repeater relay is normally energized over a circuit governed by its associated code detecting relay and by one of the two stick relays at the associated signal location. Relay HEP at.

III, for example, is normally energized over a circuit extending from one terminal of the unidirectional source through back contact I8 of relay WS, front contact 25 of the associated code detecting relay HE, and the winding of relay HEP to the other terminal of the source. Similarly, relay HWP at III is energized over a circuit extending from one terminal of the unidirectional source through back contact 2! of relay ES, front contact 22 of the associated code detecting relay HW and the winding of relay HWP to the other terminal of the source.

The relays HEP and DE associated with relay TR of section B may be utilized, as indicated, for controlling the associated wayside signal SEIII positioned at III and governing traffic in section B. When both relays HEP and DE are picked up, signal SEIII may, for example, be caused to display its clear aspect, when relay HEP is picked up but relay DE is released, the signal may be caused to display its approach aspect, and when both relays HEP and DE are released, the signal may be caused to display its stop aspect. Since signal SEIII governs eastbound traffic in section B and. is controlled by relay TR of section B through the medium of the associated relays HEP and DE, relay TR may be termed an eastbound track relay and the track circuit with which this relay is associated may likewise be termed the eastbound track circuit of section B.

The other track relay TRA of section B controls through the medium of its associated decoding transformer DTW and its relays DW and HWP the associated wayside signal SWIV positioned at IV and governing westbound trafiic in section B. The control of signal SWIV established by relays I-IWP and DW may be similar to that heretofore described with respect to signal SEIII, and since signal SWIV governs westbound trafiic in section B, the associated track relay TRA may be designated a westbound track relay and its associated track circuit may be designated as the westbound track circuit of section B.

The decoding apparatus associated with relay TR at 111 further incorporates means for generating a feed back code. These means are described in detail in our copending application, Serial No. 386,632, and it is deemed sufficient for the present application to state that when relay TR follows frequency type code energy received from section B, each release of relay TR caused by an off interval of the frequency type code causes the associated code repeating device RC to be momentarily energized and picked up. The device RC connects, over its contacts 26 and 21 in their released or back positions, relay TR to the associated track transformer TTW, hence the picking up of device RC is effective to uncouple relay TR from the track rails and connects over these contacts closed in their front positions and front contact 48 of the associated relay HE, transformer TTW to the source of track circuit energy designated by the reference character BK-CX, thereby causing to flow in the track rails of section B a relatively short pulse of feed back code energy during each off interval of the frequency type code. As previously mentioned, however, the device RC at times is caused to operate in response to code generating means capable of generating frequency type codes, hence at such times section B is provided at its end III with frequency type code energy due to operation of device RC in a'manner to be explained presently. When device RC is caused to operate in response to the code generating means, the track circuit energy supplied to the associated section is then derived from the heretofore mentioned source indicated by the terminals BXCX and is furnished through the previously mentioned transformer EWS.

In the normal condition of the apparatus, as represented in the drawings, device CTP at. IV associated with relay TRA is energized over a circuit which includes a contact of coder HBGCT',

hence device CTP is caused to beintermittent- 1y energized at a rate corresponding to the 180 code rate. A circuit over which device CTP is normall caused tooperate at the 180 code rate maybe traced from one terminal of the unidirectional source through contact I of coder I8BCT, front contacts 28 and 29 of relay HEP and the winding of device CTP to the other terminal of the source. Each time device CTP is energized, its front contacts 353 and 3| close and connect the source BXCX through transformer EWS to transformer TTE over a circuit which may be traced from terminal BX through contact I8Ela of coder 1811GT, front contact 32 of relay HEP, windings 5 and 6 in series of transformer EWS, front contact 30 of device CTP, the primary winding of transformer winding TTE. and front contact 3| of device CTP to the other terminal CX of the source. At such times, therefore, as device CTP is energized, an on impulse of frequency type code energy is supplied through transformer TTE to section .B. This energy impulse is transmitted through the track rails to the opposite end of the section where it is supplied through transformer TTW and back contacts 26 and 2! of device RC to relay TR, thereby causing that rela to pick up.

Each time device CTP at IV is deenergized, its front contacts 30 and 3| open to disconnect the source BXCX from transformer TTE, thereby producing in section B an off interval of the frequency type code. Back contacts 39 and 3| of device CTP now close to connect relay TRA at IV in circuit with trans-former TTE At the opposite end of the section, relay TR is of course caused to be released due to the off interval of the frequency type code, and the release of this relay causes the associated device RC to be momentarily energized, thereby disconnecting relay TR from transformer TTW and connecting the source BKCX- to such transformer. This causes to flow in section B a short impulse of feed back code energy which istransmitted through the track rails to the other end IV of the section where it is supplied through transformer TTE to relay TR'A, thus causing relay TRA to pick up. Device RC at III is arranged to release and reconnect relay TR- at III to transformer TTW prior to device CTP at the opposite end of the section being reenergized to cause another on interval of frequenc type code energy to flow in the track rails. Under the above assumed conditions, therefore, relay TR. at III iscaused to operate at the code rate in response to frequency type code energy supplied to section B at IV due to the operation of code repeater device CTP at the 180 code rate, while relay TRA at III is caused to operate at the 180 code rate in response to feed back type code energy supplied at III to section B in response to the operation of relay TR at the 180 code rate. Decoding relays HE and DE and the repeater relay HEP associated with relay TR at III accordingly are energized, and signal SEIII is caused to display its clear aspect.

Decoding relay I-IW associated with relay TRA at IV is energized, slow acting repeater relay I-IWP associated therewith likeWiseis energized, but the associated decoding relay DW is released since its energizing circuit is held open at back contact 34 of relay HEP associated with section C, for a purpose not material to the present invention. Signal SWIV accordingly is caused to displa its approach aspect.

The track circuit apparatus provided for sec' tions A and C is arranged in a manner substantially corresponding to that heretofore described for section B, but only the apparatus of section A located at its westbound entrance end III and the apparatus of section C located at its eastbound entrance end IV are represented in the drawings. These represented portions of the track circuit apparatus of sections A and C of course are caused to operate normally in a manner substantially corresponding to that heretofore explained in connection with the corresponding portions of the track circuit apparatus of section B.

The apparatus just described is arranged in a manner explained in detail in our copending application, Serial No. 386,632, so that when an eastbound train enters the stretch and shunts the rails of the first section of the stretch, in each of the remaining sections track circuit energy is removed from the track circuit associated with the opposite direction of train movement. For example, the apparatus is arranged so that when an east bound train enters the stretch, the feed back code energy normally supplied to section A is disconnected with the result that relay TRA at III becomes inactive, relays I-IW and HWP associated therewith become released, signal SWIII is caused to display its stop aspect, and the previously traced circuit of relay ES is completed whereupon relay ES is coupled through rectifier 9 and transformer EWS to the track circuit source BXCX which is normally utilized to supply frequency type code energy to the rails of section A.

A like action takes place in section B with the result that relay TRA at IV is inactive, decoding relay HW and repeater relay HWP associated therewith release, signal SWIV is controlled to display its stop aspect, and relay ES at IV is coupled through rectifier 9 and transformer EWS to the source BX-CX at location At this time, relay ES at IV has applied thereto an electromotive force caused to be induced in secondary winding 8 of its associated transformer EWS due to the track circuit energy normally supplied from the source BX-CX through transformer EWS to section B, but relay ES is so proportioned as to be ineffectively energized by the electromotive force induced in winding 8 of transformer EWS under the assumed conditions. Similarly, relay ES at III has applied thereto an electromotive force caused to be induced in winding 8 of its associated transformer EWS by the supply of track circuit energy to section A, butES AT III is proportioned so as to be ineffectively energized if section A is unoccupied.

When, however, the train enters section A and establishes through its wheels and axles a low resistance path across the track rails, the current supplied through transformer EWS to the rails of the associated section increases in magnitude, and as the train advances into the sec-. tion to shunt out more and more of the track rail impedance connected in circuit with track transformer TTE, the rail current continues to increase until it reaches a value sufiicient to cause the electromotive force induced in winding 8 and applied to relay ES, to become effective to establish in relay ES its pick-up energy level. Winding 6 of transformer EWS through which current is suppliedto section A is provided and gsoaass may be utilized either to aid or oppose, the elec-' tromotive force in primary winding 5 to adjust the current supplied through transformer EWS to section A to reach a value sufficient to cause the pick-up of relay ES when and only when the train reaches at least a given point in .the track section, say,.for example, not less than 1000 feet from its eastbound exit end III. The point in the section at which relay ES is caused to pick up might, of course, vary with track ballast conditions, but by properly proportioning relay ES and transformer EWS, the relay may be caused to pick up within the relatively small limits of, say, 1000 to 1500 feet from the exit end III of the section.

When relay ES picks up, its front contact 16 closes to complete its previously traced preliminary stick circuit which is effective to hold relay ES energized during the off intervals of the coded track circuit energy supplied to section A. The train under ordinary conditions will occupy section B and shunt relay TR to cause relay HE associated therewith to release and close its back contact l4, thereby complet ing the previously traced final stick circuit of relay ES, prior to relay HW picking up upon section A being vacated. Ordinarily, therefore, the final stick circuit of relay ES is completed before relay HW picks up to open its back contact H and thereby open the preliminary stick circuit of relay ES. In the event, however, that a short lightweight train passes rapidly from section A into section B, relay HW associated with section A might be caused to pick up prior to the train shunt on relay TR, causing the release of relay HE at III. In such event, the previously mentioned snubbing path including asymmetrical unit 23 and front contact I3 of relay HEP functions to provide a low resistance path across relay ES during the transfer time of contact ll of relay HW from its back to its front position. This low resistance path serves to snub the release of relay ES, and after front contact II of relay HW closes, an alternate snubbing path is then completed in which front contact ll of relay HW and back contact 12 of relay HWP are connected in multiple with asymmetrical unit 23. By virtue of these snubbing circuits, relay ES is made sufficiently slow releasing to bridge the off intervals of the coded energy supplied through transformer EWS to section A, and when relay HE drops the final stick circuit of relay ES is completed so that relay ES is maintained energized until section B becomes vacated.

Relays DE and HEP also release when relay TR becomes shunted by the train in section B, and signal SEIII accordingly is caused to display its stop aspect. With both relays I-IWP and HEP at III released, and relay ES at III picked up, the associated code repeating device CTP is caused to operate at the code rate over a circuit extending from one terminal of the unidirectional source through contact 15 of coder T, back contact 36 of relay HWP, back contact 28 of relay HEP, front contact 31 of relay ES, and the winding of device CTP to the other terminal of the source. After the train vacates section A, this 75 code energy is available in section A and functions to cause relay TRA to operate and pick up the associated decoding relay HW, in a, manner to be made clear presently.

The train advancing through section B of course causes the rail current suppliedto such section at IV through transformer EWS to increase, and when the train reaches the predetermined point in the section, relay ES-at IV is caused to pick up over its previously traced pickup circuit and establishes its previously mentioned preliminary stick circuit. Relay ES at IV is held energized over its final stick circuit completed when relay HW at IV releases due to the train entering section C and shunting relay TR associated therewith. Relay I-IEP at IV also releases to condition the associated apparatus to supply '75 code energy to section B. When the train vacates section B, this '7 code energy causes operation of relay TR at III, whereupon relay I-IE associated therewith is caused to pick up and open the previously mentioned final stick circuit of relay ES at III, hence relay ES drops to complete the previously traced circuit of relay HWP. Relay HEP at III likewise is energized when relay HE picks up, and with both repeater relays HEP and IIWP picked up, device CTP at III is caused to operate at its normal 180 code rate to supply 180 code energy to section A, with the result that relay TRA at III operates also at the 180 code rate, as will be made clear presently.

In addition, the energization of relays HEP and HWP at III causes signals SEIII and SW'III to display their respective approach aspects, and also condition the apparatus at III to cause device RC to operate at the rate corresponding to the rate of operation of its associated relay TR to supply section B with feed back energy coded at the 75 code rate. This feed back energy causes relay TBA at IV to operate and pick up its associated code following relay HW.

When the train vacates section C, relay TR at IV responds to the '75 code energy available in section C and causes relay HE associated therewith to pick up. Relay ES at IV accordingly is caused to release, relays I-IWP and HEP at IV are caused to pick up, signals SEIV and SWIV are caused to display their respective approach aspects, and code repeater-device CTP at IV is caused to operate at the 180 code rate. Relay TR at III thereupon responds to the 180 code energy available in section B, and both relays HE and DE associated therewith are picked up so that signal SEIII is caused to display its normal clear aspect. The operation of relay TR at III at the 180 code rate of course causes device RC also to operate at a corresponding rate to supply section B with 180 code feed back energy which causes relay TRA of section B to respond. The apparatus at III accordingly is restored to its normal condition as represented in the drawings.

The apparatus at IV likewise is restored to its normal condition when 180 code energy is made available in section C in response to a train vacating the section next in advance of section C.

From the foregoing description, it is readily apparent that the relays ES associated with the eastbound signals SE of the stretch are successively caused to be picked up as an eastbound train proceeds along the stretch, and also that each of these relays when picked up effect-s control of the supply of track circuit energy to the section in the rear in such manner. as to cause the signal governing eastbound traffic in the rear section to display an aspect more restrictive than clear but less restrictive than stop, thereby permitting following eastbound trains to proceed under permissive signal indications governed by traffic conditions in advance.

In addition, it is to be noted that each stick relay ES is arranged to pick up prior to the train entering the section governed by its associated signal. This advance or approach control of stick relays is effective to condition such relays to establish the proper directional control and prevent possibility of loss of such control should a short lightweight train pass rapidly from the rear section into the section governed by the associated signal. In such event, proper directional control will be established even though the track circuit apparatus of the rear section might respond to track circuit energy available therein to effect the associated relays interposed in the circuits of the associated stick relays, prior to the track circuit apparatus of the then occupied section responding to the applied train shunt.

The apparatus represented in the drawings is further arranged, as explained in detail in our copending application, Serial No. 386,632, so that when a section is deprived of frequency type code energy due to a train entering the stretch, the feed back type code energy normaliy supplied to the other track circuit of the section is replaced by frequency type code energy. For example, if a westbound train enters the stretch, all of the eastbound track circuits of the represented sections A, B and C are deprived of track circuit energy. The eastbound track circuits of these sections are normally supplied with frequency type code energy, hence the associated track relays TR incorporated therein are caused to become inactive and the associated decoding relays HE and DE are caused to release. The eastbound signals SE accordingly are caused to display their respective stop aspects, and the associated slow acting repeater relays HEP are likewise caused to be released.

Under the above assumed conditions, relay TR at location IV, for example, is inactive, relays DE, HE and HEP associated therewith are released, and device RC associated therewith is caused to operate at the 180 code rate over a circuit extending from terminal plus through contact I of coder 1813GT, front contact 36 of relay HWP, back contact 28 of relay HEP, back contact 38 of relay HE, front contact 39 of relay HWP and the winding of device RC to the other terminal of the source. With relay HE at IV released, its front contact 40 is opened to disconnect from transformer TTW track circuit source BK-CX, which source normally is utilized to supply feed back code energy to section C. Track circuit source BX-CX, normally utilized to supply frequency type code energy at IV to section B, is now intermittently connected to transformer TTW over a circuit extending from terminal BX through contact [86a of coder IBOCT, front contact 4! of relay HWP, back contact 32 of relay HEP, windings 5 and l in series of transformer EWS, back contact an of relay HE, front contact 21 of device RC, the primary winding of transformer TTW and front contact 26 of device RC to the other terminal CX of the source. It follows, therefore, that under the assumed conditions frequency type code energy is supplied through transformers EWS and TTW to section C.

Also under the above assumed conditions, the previously traced pick-up circuit of directional stick relay WS at IV is completed and such relay accordingly is coupled to the track circuit source BX-CX through the medium of transformer EWS and rectifier 9. The parts are so proportioned that unless section C is occupied, the

electromotive force induced in transformerEWS and applied to relay WS is ineffective to cause that relay to pick up.

A similar operation of the apparatus occurs at location III, hence 180 code energy of the frequency type is supplied to section B at III. This 180 code frequency type energy available in the westbound track circuits of the sections may be utilized to effect control of either or both wayside and cab signal apparatus. That is to say, the 180 code energy supplied to section B causes the operation of relay TRA at IV at the 180 code rate, and with relay HE at IV released, both relays HW and DW associated with relay TRA are picked up. Signal SWIV associated therewith accordingly is caused to display its clear aspect. The 180 code frequency type energy supplied at IV to section C is available either to control wayside apparatus (not shown), when the section is unoccupied or train-carried cab signal apparatus when the section is occupied.

When a westbound train occupies section C, the wheels and axles of the train establish a low resistance path across transformer TTW and causes a relatively heavy rail current to flow in section 0, and as the train proceeds through the section to shunt out more and more of the track rail impedance, the rail current continues to increase in magnitude. The parts of transformer EWS and relay WS are so proportioned that when the train reaches a predetermined point, substantially 1000 feet from the westbound exit end IV of the section, the increased rail current drawn through windings 5 and 1 of transformer EWS causes the electromotive force induced in secondary winding 8 of transformer EWS to reach a value suflicient to pick up relay WS. Winding 1 of transformer EWS may be utilized to adjust the value of rail current drawn so as to efiect the pick-up of the associated relay -WS at the desired location in the section. When relay WS picks up, it completes its previously traced preliminary stick circuit which holds relay WS energized during the ofi intervals of the frequency type code energy supplied to section C.

When the train enters section B, relay TRA is shunted, relays HW, DW and HWP associated therewith release, signal SWIV is caused t display its stop aspect, and the previously mentioned final stick circuit of relay WS is completed. Device RC at IV is now conditioned to operate at the 75 code rate over a circuit extending from one terminal of the unidirectional source through contact 75 of coder 750T, back contact 36 of relay HWP, back contact 28 of relay HEP, back contact 38 of relay HE, front contact 42 of relay WS and the winding of device R to the other terminal of the source, and when the train vacates section C this energy is made available to restore the track circuit apparatus of this section to its normal condition, as will be made clear presently. The previously traced snubbing circuits of relay WS at IV are effective should a short lightweight train pass rapidly from section C into section B, to delay the release of relay WS and thereby prevent possible loss of directional control in the event that relay HE at IV picks up before relay HW at IV is caused to release by the train shunt on relay 'IRA.

The train in proceeding through section B causes the rail current supplied thereto through windings 5 and l of the associated transformer EWS to increase until the electromotive force caused to be induced in winding 8 of transformer EWS reaches a value sulficient to pick up relay WS at B1, whereupon that relay completes its previously traced preliminary stick circuit. When the train enters section A, relay TRA becomes inactive, relays DW, HW and HWP associated therewith release, signal SWIII is caused to display its stop aspect, and the previously traced final stick circuit of relay WS is completed. Device RC at III is caused to operate at the code rate over a circuit corresponding to that heretofore traced for device RC at IV.

After the train vacates section B, relay TRA at IV responds to the 75 code frequency type energy supplied to section B, and picks up relay HW associated therewith to cause signal SWIV to display its approach aspect. Relay HW also completes at its front contact 22 the previously traced circuit of its associated repeater relay HWP to energize that relay, and opens at its back contact i9 the previously traced stick circuit of relay WS. Relay WS at IV accordingly releases, thereby completing at its back contact Hi the previously traced energizing circuit of repeater relay HEP at III. With both repeater relays HWP and HEP at IV picked up, device CTP at IV is energized over its previously traced normal circuit including contact I89 of coder iBGCT, whereupon 180 code frequency type energy is supplied at IV to section B. Relay TR at III responds at least to a portion of this 180 code frequency type energy to pick up relay HE associated therewith. When relay HE picks up, it opens its back contact 38 to interrupt the previously mentioned circuit over which device RC is caused to operate at the 75 code rate, and renders effective the previously mentioned means whereby device RC is caused to operate at the rate corresponding to the rate of operation of relay TR. Relay TR accordingly follows the 180 code frequency type energy available in section B, to cause relays HW and DW associated therewith to pick up, and to'operate device R0 at the 180 code rate to cause l'c0de feed back type energy to be supplied to section B. Relay TBA at IV operates in response to the code feed back type energy available in section B, but with relay HE at IV picked up, only relay HW associated With relay TRA is energized and as a result signal SWIV is caused to display its normal approach indication. The track circuit apparatus of section B accordingly is restored to its normal condition wherein 180 code frequency type energy is supplied to the eastbound track circuit of the section to cause operation of relay TR at the 180 code rate, and 180 code feed back type energy is suppliedto the westbound circuit of the section to cause operation of relay 'IRA at the 180 code rate. At this time, however, relay HEP at III is released since its energizing circuit is open at back contact It of relay WS, and as a result signal SEIII is caused to display its stop aspect.

The track circuit apparatus of section A is similarly restored to its normal condition when the westbound train vacates section A. When this happens, relay TRA operates in response to coded energy available in section A, and relay HW associated therewith picks up to release relay WS at III. Repeater relays HWP and HEP accordingly are caused to pick up, and device CTP at III is caused to operate at its normal 180 code rate over its previously traced normal circuit. Signal SWIII accordingly is caused to display its normal approach aspect, while signal SEIII is caused to display its normal clear aspect.

From the foregoing, it is readily apparentthat.

the westbound stick relays WS are successively caused to be picked up as a westbound train proceeds along the stretch, and also that each of these relays when picked up functions to condition the track circuit apparatus of the associated section to be restored to its normal condition after the westbound train vacates such section. In addition, it should be noted that the apparatus is arranged in such manner that the eastbound signal immediately in the rear of a westbound train is caused to display its stop aspect, in accordance with the usual principle of A. P. B. signaling.

When a westbound train on the stretch is being followed by another train, each westbound stick relay WS functions in a manner similar to that pointed out heretofore in connection with the eastbound stick relays ES, to control the supply of track circuit energy to the rear section and .thus obtain the usual A. P. B. feature of permitting the second train to follow the first under permissive signal aspects.

If a second train follows a'first westbound train through the stretch, the eastbound track circuits of all sections up to the section occupied by the preceding train, are deenergized and frequency type code energy is supplied to each of the westbound track circuits of such sections, as pointed out heretofore. Assume that a westbound train occupies section A, and that the first train is being followed by a second. The second train causes the eastbound track circuits of sections B and C to be deener-gized, so that relays TR of such sections are released. Under the assumed conditions, relay WS at III is energized over its stick circuit, relays HWP, HEP, HW and HE at III are released, and code repeating device RC at III is energized over its previously traced circuit including contact of the associated coder 150T. The westbound track circuit of section B accordingly is supplied with frequency type energy coded at the 75 code rate, and relay TRA at IV in response picks up relay HW associated therewith to operate signal SWIV to its approach aspect. Code repeating device RC at IV is now energized over a previously traced circuit including contact l80 of coder I80CT, so that 180 code frequency type track circuit energy is supplied to the westbound track circuit of section 0. This energy is of course available when section C is unoccupied, to cause operation of Wayside apparatus associated with section 0, or if the second train occupies section 0, to operate the traincarried apparatus on the train to cause a display of its clear indication. It is readily apparent, therefore, that apparatus embodying our invention is arranged to incorporate the usual A. P. B. feature of directional control that becomes effective when a westbound train enters a stretch, to permit following Westbound trains to proceed under permissive signal indications governed by trafiic conditions in advance. In addition, it is apparent that the westbound directional stick relays WS are arranged to be approach energized and each is caused to be picked up prior to the train entering its associated section, thereby avoiding possible loss of directional control due to a short lightweight train passing rapidly from one section into the next.

In addition, it is to be noted that the directional control apparatus embodying our invention is particularly suitable for use in A. P. B. systems of signaling involving apparatus arranged to eliminate all control line wires and controlled wholly through the medium of track circuits.

.One feature of apparatus arranged inaccordance for coupling the stick relays associated with the direction of traffic to the track circuitenergy sources utilized to energize the track circuit governing traffic in the direction of the trafiic movement. Ihis permits not only directional control or energization of stick relays to be obtained whereby only the eastbound stick relays are picked up for eastbound moves and westbound stick relays are picked up for westbound moves, but also enables an approach control of such re- .lays'to be obtained, therebyreducing the possibility of lossof directional control when the stretch .is occupied by short lightweight trains.

Additionally, the feature of coupling the stick relays to the track circuit sources permits control of such relays to be effected without reducing or decreasing the effective lengths of the associated .track circuits. In previously proposed systems where floating track relays are interposed in the track circuits, such relays absorb a portion of the available energy at the track rails and introduce resistanceor impedance in the circuits which tends to reduce the effective length .of such circuits. .In our arrangement, however,

energy for the stick relays is derived from the circuit supplying the primary winding of the associated track transformer, and this arrangement of course has no effect upon the secondary winding of the transformer insofar as introducing resistance or impedance in the associated track circuit. It follows, therefore, that our invention may be incorporated into railway track circuits without reducing or decreasing the effective lengths of such circuits.

Although we have herein shown and described only one form of railway traffic controlling apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we .claim is:

1. Directional control apparatus for use in a signal .system provided for a stretch of single track railway divided into successive adjoining track sections, said signal system being characterized by the provision of a source of track .circuit energy at the adjacent ends of each two adjoining track sections, said directional control apparatus comprising the combination with each track circuit energy source of two directional stick relays one for onedirectionof traffic in .one ofItheassociated .two sections and the other forithe opposite direction of traffic in the other ;of the associated two sections, and apparatus controlled by a train entering thestretchand shunting the rails of the first section for supplying each oneof the stick relays associated with the. direction of the train movement with energy derived fromits associated source and having a valuedependent upon the position of thetrain shunt in the associated sectionand varying in magnitudeas the train proceeds through thesection.

disconnecting said source from said one section and connecting such source to the rails of the other section, two stick relays one for each code detecting relay, coding means, means controlled by said repeater relays for causing the energy supplied from said source to the track rails of either section to be coded by said coding means, coupling means for connecting said stick relays to receive energy from said track circuit source, a pick-up circuit for each directional stick relay including said coupling means and controlled .by said code detecting relays and the associated repeater relays for coupling the one of said two stick relays associated with the direction of train movement to said source upon a train entering said stretch, a first stick circuit for each stick relay including its own front contact and. a front contact of the repeater relay of its associated code detecting relay, and another stick circuit for each stick relay including its own front contact and controlled by its associated code detecting relay.

3. Apparatus for use at an intermediate signal location in an absolute permissive block railway signal system, said location being defined by the adjacent ends of two adjoining track sections,

comprising a track relay at the adjacent end of one of said two sections and another track relay at the adjacent end of the other of said two sections, two code detecting relays one for each track relay and each controlled by its associated track relay to detect a code operation of such relay, two slow acting repeater relays one for each code detecting relay, a track circuit source, means controlled by one of said two repeater relays associated with one of said two sections for normally coupling said source to the rails of the other of said two sections, coding means for coding the energy supplied from said source, means controlled by the code detecting relay associated with the said one repeater relay ,for at times coupling said source to the rails of the asociated section, two directional stick relays one for each code detecting relay, coupling means interposed in the connection of said source to the rails of either of said sections for coupling said stick relays to receive coded energy from said source; a pick-up circuit for each stick relay including said coupling means, a back contact of the other stick relay, back contacts of the other code detecting relay and its associated repeater relay and a front contact of the repeater relay of the associated code detecting relay, a first stick circuit for each stick relay including a front contact of such relay and another source of energy and a front contact of the repeater relay of the associated code detecting relay, and another stick circuit for each stick relay also including said other source of energy and a front contact of said stick relay and a back contact of its associated code detecting relay.

, 4. Apparatus for use at an intermediate signal location in an absolute permissive block railway signal system, said location being defined by the adjacent ends of two adjoining track sections,

comprising a track relay at the adjacent end of one of said two sections and another track relay at the adjacent'end of the other of said two sections, two code detecting relays one for each track relay and each controlled by its associated track relay to detect a code operation of such relay, two slow acting repeater relays one for each code detecting relay, code generating means controlled by said two repeater relays for supplying to one of said two sections track circuit energy coded at a rate corresponding to the rate of operation of the track relay of such section, a track circuit source, means controlled by said two repeater relays for normally coupling said source to the other of said sections, means for coding the energy supplied from said source, means controlled by the code detecting relay associated with the said one track section for at times rendering saidcode generating means ineffective and for coupling said source to the said one track section, a transformer having one winding interposed in the connection of said source to either of said sections, another winding for said-transformer inductively coupled with said one winding, two stick relays one for each code detecting relay, pick-up circuits for connecting each of said stick relays to receive energy from said other winding of said transformer, the pick-up circuit of each stick relay including a back contact of the other stick relay and a front contact of the repeater relay of its associated code detecting relay as well as a back contact of the other repeater relay, a preliminary stick circuit for each stick relay, the preliminary stick circuit of each stick relay including its own front contact and another source of energy as well as a back contact of the other code detecting relay and a front contact of the repeater relay of its associated code detecting relay, means for at times providing shortcircuiting paths across said stick relays to delay their release, and final stick circuit for each relay comprising its own front contact and a back contact of its associated code detecting relay.

5. In a railway signal system for a stretch of single track railway divided into successive adjoining track sections, said system having a plurality of sources of track circuit energy one at the adjacent ends of each two adjoining track sections, said system having means for providing each of said sections with two track circuits one for one direction and the other for the other direction of traffic, and said system having means responsive to a train entering said stretch and shunting the rails of the first section for connecting each of said energy sources in circuit with the rails of the track circuit for the direc tion of train movement in the one of the two adjoining track sections, the combination in such asystem of two stick relays for each of said energy sources, one stick relay for one direction of traffic and the'other stick relay for the opposite direction of traific, and means governed by said train responsive means and effective when a train enters said stretch for coupling each of the stick relays for the. direction of the train movement to the circuit connection of its associated source to the rails of the associated one of the two adjoining sections, said coupling means being effective to supply each of said coupled stick relayswith energy having a value dependent upon the position of the train in the associated section and adjusted to pick up each stick relaywhen the train reaches an intermediate point in the associated section.

In combination, a stretch of railway track including two-adjoining insulated track sections, a source of energy at the junction of said sections, means for normally connecting said source in circuit with the rails of one of said two sections for establishing a track circuit eii'ective to govern traflic in one direction in said one section, means responsive toa train entering said stretch in the opposite direction for disconnecting said source from the rails of said one section and for connecting said source to the rails of the other of said sections for establishing a track circuit effective to govern trafiic in said opposite direction in said other section, two directional stick relays one for each direction of traffic in said sections, and means responsive to a train entering said stretch for coupling the stick relay associated with the direction of train movement to the circuit connection of said source to the rails of the associated section, said coupling means being effective to energize the coupled stick relay at a current value below its pick-up value until the train occupies the associated section and establishes a low resistance shunt in said section whereby to cause said current value to reach said pick-up value due to the increased track circuit current caused to flow in said associated section.

7. Directional control apparatus for use in a signal system provided for a stretch of single track railway divided into a plurality of successive adjoining track sections, said system having a plurality of sources of track circuit energy one at the junction of each two track sections, said system having means for normally connecting each of said sources in circuit with the rails of one of its associated two sections for establishing a track circuit effective to govern traffic operating in one direction in such section, and said system having means responsive to a train entering said stretch in the opposite direction for disconnecting each of said sources from the rails of its said associated one section and for connecting each of said sources in circuit with the rails of the other of its associated sections for establishing a track circuit effective to govern trafiic in said opposite direction in such section, said directional control apparatus comprising two stick relays for each of said energy sources, one stick relay for one direction of traffic and the other stick relay for the opposite direction of traffic, means responsive to a train entering said stretch for coupling each of the stick relays for the direction of train movement to the circuit connection of its associated source to the rails of the associated one of the two sections, each of said coupling means being effective to derive from the associated circuit connection energy having a value inefiective to pick up the coupled stick relay until the train establishes a shunt in said associated one track section, and means governed by the track circuits of each two sections for holding each of said coupled stick relays energized until the train vacates the other of its associated two sections.

8. In combination, a stretch of railway track including two adjoining insulated track sections, a source of energy at the junction of said sections, means responsive to traffic on said stretch for connecting said source in circuit with the rails of one or the other of said two sections according as traffic operates over said stretch in one direction or the other, two stick relays one for each direction of trafiic over said stretch,

and -means responsive'to traffic on-said stretch sis and effective when a train enters said stretch for coupling the one stick relay associated with the direction of train movement to said source in a pick-up circuit which derives from said source energy having a value below the pick-up value of such relay, said means being adjusted to cause said energy to reach the pick-up value of said relay when the train establishes a shunt in'the'section to which said source is connected.

9. In combination, a stretch of railway track including two adjoining insulated track'sections, a source of energy at the junction of said sections, means responsive to traffic on said stretch for connecting said source in circuit with the rails of one or the other of said two sections according as traffic operates over said stretch in one direction or the other, two stick relays one for each direction of traffic over said stretch, means responsive to trafiic on said stretch and efiective when a train enters said stretch for coupling the one stick relay associated with the direction of train movement to said source in a pick-up circuit which derives from said source energy having a value below the pick-up value of such relay, said means being adjusted to cause said energy to reach the pick-up value of said relay when the train establishes a shunt in the section to which said source is connected, and means also responsive to traffic on said stretch for energizing said coupled stick relay over a stick circuit until the train vacates the other of said two sections.

10. In combination, a stretch of railway track including an insulated track section, 'a source of energy at a given end of said section, a first direction track circuit for said section comprising means at said given end of said section for supplying the section rails from said source with recurring pulses of master code energy that are separated by off period intervals and means at the opposite end of said section responsive to said master energy pulses, a second direction track circuit for said section comprising means at said opposite section end which during and only during reception of said master code pulses supply the section rails with pulses of feed back energy that recur in step with the said off periods of the received master code and means at said section given end responsive to said feed back pulses, means responsive to trafiic on said stretch and effective when a train enters said stretch in said first direction for removing said feed back pulses from said section, a relay, and means governed by said feed back pulse responsive means effective when said feed back pulses are removed from said section for inductively coupling said relay to said source for deriving energy therefrom having a value sufficient to pick up said relay when and only when said train establishes a shunt in said section and thereby causes an increased value of energy to flow in the rails of said section.

11. In combination, a stretch of railway track including two successive adjoining insulated track sections, a first direction track circuit for each of said sections comprising means at the 'sections given end which supply thesection rails with recurring pulses of master code energy that are separated by ofi period intervals and means at the sections opposite end responsive to said master code pulses, a source of energy at the junction of said sections, saidsource supplying energy to the first direction track circuit of the i one section that has its given end at the junction of said sections; a second direction track circuit for said one section comprising means atthe sections opposite end controlled by the master code pulse responsive means of said one section to be effective during and only during reception of said master code pulses to supply the section rails with pulses of feed back energy that recur in step from said one section, a relay at the junction of said sections, means governed by said feed back pulse responsive meansof said one section efiective when said feed back pulses are removed from said one section for inductively coupling. said relay to said source for deriving therefrom energy.

having a value sufficient to pick up said relay when and only when said train shunts said one section to cause a relatively high value of rail energy to flow, and a stick circuit including a front contact of said relay and governed by said master code pulse responsive means of the other of said two sections for maintaining said relay energized until said train vacates said other section.

12. In combination, a stretch of railway track including a plurality of successive adjoining insulated track sections, a first direction track circuit for each of said sections comprising means at the sections given end which supply the section rails with recurring pulses of master code energy that are separated by off period intervals and means at the sections opposite end responsive to said master code pulses, a plurality of sources of energy one at the junction of each two adjoining track sections, each of said sources supplying energy to the first direction track circuit of the one section of the adjoining two sections that has its given end at the junction of said adjoining two sections, a second direction track circuit for each of said sections comprising means at the sections opposite end controlled by the master code pulse responsive means of such section to be effective during and only during the reception of said master code pulses to supply the section rails with pulses of feed back energy that recur in step with the off periods of said master code pulses and means at the sections given end responsive to said feed back pulses, a plurality of directional stick relays two for each of said sources of energy, means controlled by said track circuits efiective when a train enters said stretch in said first direction for removing said feed back pulses from each of said track sections, means controlled by said feed back pulse responsive means of each section for inductively coupling one of the two stick relays associated with the source at the given end of such section to such source for deriving therefrom energy having a value sufficient to pick up such relay when and only when said train establishes a train shunt in the associated section, means controlled by said track circuits effective when a train enters said stretch in said second direction for removing said master code pulses from each of said sections and effective to replace the feed back pulses in each of said sections with a special code energy pulse derived from the source located at said opposite sections end, and means controlled by the master code pulse responsive means of each section for inductively coupling the other one of the two stick relays associated with the source at the sections opposite end to such source for deriving therefrom energy having a value sufiicient to pick up such relay when and only when said second direction train establishes a train shunt in the associated section.

13. In combination, a stretch of railway track including a plurality of successive adjoining insulated track sections, a first direction track circuit for each of said sections comprising means at the sections given end which supply the section rails with recurring pulses of master code energy that are separated by off period intervals and means at the sections opposite end responsive to said master code pulses, a plurality of sources of energy one at the junction of each two adjoining track sections, each of said sources supplying energy to the first direction track circuit of the one section of the adjoining two sections that has its given end at the junction of said adjoining two sections, a second direction track circuit for each of said sections comprising means at the sections opposite end controlled by the master code pulse responsive means of such section to be effective during and only during the reception of said master code pulses to supply the section rails with pulses of feed back energy that recur in step with the off periods of said master code pulses and means at the sections given end responsive to said feed back pulses, a plurality of directional stick relays two for each of said sources of energy, meanscontrolled by said track circuits eifective when a train enters said stretch in said first direction for removing said feed back pulses from each of said track sections, means controlled by said feed back pulse responsive means of each section for inductively coupling one of the two stick relays associated with the source at the given end of such section to such source for deriving therefrom energy having a value sufi'icient to pick up such relay when and only when said train establishes a train shunt in the associated section, means controlled by the said master code pulse responsive means of each section for energizing the said one stick relay at the said opposite end of such section over a stick circuit until the said train vacates such section, means controlled by said track circuits effective when a train enters said stretch in said second direction for removing said master code pulses from each of said sections and effective to replace the feed back pulses in each of said sections with a special code energy pulse derived from the source located at said opposite sections end, means controlled by the master code pulse responsive means of each section for inductively coupling the other one of the two stick relays associated with the source at the sections opposite end to such source for deriving therefrom energy having a value suflicient to pick up such relay when and only when said second direction train establishes a train shunt in the associated section, and means controlled by the said feed back pulse responsive means of each section for energizing the said other stick relay at the said given end of such section over a stick circuit until the said second direction train vacates such section.

14. In combination, a stretch of railway track divided into a plurality of successive adjoining insulated track sections, a plurality of sources of energy one at the junction of each two adjoining sections, a first direction track circuit for each; of said sections comprising means at the sections given end for supplying master type energy from the one of said sources at such end to the section rails and means at the section's opposite end responsive to such master type energy, a second direction track circuit for each of said sections comprising means at the section's opposite end controlled by the master energy responsive means of such section to supply the sections rails with another type of energy and means at said sections given end responsive to such other type of energy, a plurality of directional stick relays two for each of said energy sources, means controlled by said track circuits effective when a train enters said stretch in said first direction for removing said other type of energy from each of said track sections, means controlled by the said other type energy responsive means of each section for inductively coupling one of the two stick relays associated with the source at the given end of such section to such source for deriving therefrom energy having a value sufiicient to pick up such relay when and only when said first direction train establishes a train shunt in said section, means controlled by said track circuits effective when a train enters said stretch in said second direction for removing said master type energy from each of said sections and efiective to replace the said other type of energy in each of said sections with a special type of energy derived from the one of said sources located at the opposite end of such section, and means controlled by the master type energy responsive means of each section for inductively coupling the other one of the two relays associated with the energy source at the opposite end of such section to such source for deriving therefrom energy having a value suflicient to pick up such other relay when and only when said second direction train establishes a train shunt in the associated section.

15. In combination, a stretch of railway track including two adjoining insulated track sections, a source of track circuit current at the junction of said sections, means for connecting said source to the rails of one of said sections, a directional stick relay, means responsive to trafiic on said stretch and effective when a train enters said stretch in a given direction for inductively coupling said stick relay to said source in a pickup circuitefiective to energize said relay from said source with current having a value below the pick-up value until said train occupies said one section and establishes a train shunt to cause an increased value of track circuit current to flow, and a stick circuit governed by trafilc in the other of said sections for maintaining said stick relay energized until said train vacates the other of said sections.

16. In combination, a stretch of railway track including two adjoining insulated track sections, a source of track circuit current at the junction of said sections, means for normally connecting said source to the rails of one of said sections, means responsive to traflic on said stretch and efiective when a train enters said stretch in a given direction for disconnecting said source from said one section and connecting said source to the rails of the other of said sections, two directional stick relays one for each of said sections, means responsive to traffic on said stretch and effective when a train enters said stretch in said given or in the opposite direction for inductively coupling one or the other of said directional stick relays respectively to said source in apick-up circuit effective to energize the coupled stick relay from said source with current having a value below the pick-up value of the relay until the train occupies the one of said two sections associated with such coupled stick relay and establishes a train shunt therein efiective to cause an increased value of track circuit current to flow, and a stick circuit governed by trafiic in the other of said two sections for maintaining such coupled stick relay energized until said train vacates such other section.

RALPH R. KEMMERER. CRAWFORD E. STAPLES. 

